The present invention broadly relates to an output shaft driven by an input shaft through a gearbox arrangement and, in particular, to such an output shaft driven in a constant rotational direction but at two different rotational speeds depending upon the particular direction of rotation of the input shaft for a given rotational speed of the input shaft.
Gearbox arrangements having an output shaft driven in a constant rotational direction but at two different rotational speeds depending upon the particular direction of rotation of the input shaft for a given rotational speed of the input shaft are well known and are disclosed, for example, by Stilin U.S. Pat. No. 4,501,169, specifically relating to belt conveyors, and Glatfelter U.S. Pat. No. 3,517,574, specifically relating to handheld power drills.
In particular, Stilin discloses a two speed gearbox arrangement driven by a reversible motor and having unidirectional output. As shown in FIG. 1 of Stilin, the input shaft (14) is coaxial with and engages the output shaft (39) via a unidirectional clutch (37) for direct driven rotation of the output shaft when the input shaft is driven in a first rotational direction. The unidirectional clutch disengages from the output shaft when the input shaft is rotated in a second, opposite rotational direction to the first direction. In that case, the input shaft includes a pinion (20) which engages a triple reduction gear unit including a first intermediate shaft (22) and first and second gears (21,23) thereof, and a second intermediate shaft (25) and first and second gears (24,26) thereof. The reduction gear unit engages and drives a gear (27) keyed to a quill shaft (16) which, in turn, is coaxially disposed about the output shaft and coupled to the output shaft via a second unidirectional clutch (32). Moreover, the second clutch is disposed coaxially to and mounted for fixed rotation with the first clutch. When the input shaft is rotated in the second direction, the second clutch is arranged to engage the output shaft for driven rotation thereof by the input shaft through the gear reduction unit. Furthermore, while the output rotational speed may differ as a result of the gear reduction unit when the rotational direction of the input shaft is reversed for a given rotational speed of the input shaft, the direction of rotation of the output shaft remains the same whether the input shaft is driven in the first or second direction.
Glatfelter discloses in FIG. 2 a gearbox arrangement having an output shaft (3) driven by an input shaft (6) through selective coupling via a unidirectional clutch (8), whereby rotation of the input shaft in a first rotational direction results in direct driven rotation of the output shaft, but whereby rotation of the input shaft in a second, opposite rotational direction to the first direction does not result in direct driven rotation of the output shaft. Instead, the input shaft includes pinion (10) which engages and drives a gear reduction unit, including intermediate shaft (19) having first and second gears (20,22). In particular, first gear (20) is mounted to the intermediate shaft via a second unidirectional clutch (21) and second gear (22) engages a pinion (5) axially disposed on the output shaft. The second clutch is arranged such that rotation of the input shaft in the second direction results in coupled engagement between the first gear of the gear reduction unit and the pinion of the input shaft for driven rotation of the output shaft through the gear reduction unit. Again, while the output rotational speed may differ as a result of the gear reduction unit when the rotational direction of the input shaft is reversed for a given rotational speed of the input shaft, the direction of rotation of the output shaft remains the same whether the input shaft is driven in the first or second direction.
The present invention advances the state-of-the art by providing an additional gearbox arrangement that accomplishes the same input/output characteristics as the gearbox arrangements of Stilin and Glatfelter, but with a simpler and more economical structure specifically accommodating a floor maintenance machine. In this regard, patents are known to disclose floor maintenance machines, some of which have gearbox arrangements exhibiting the same characteristics of the input and output shafts discussed above, but none of which disclose or suggest the particular gearbox arrangement and floor cleaning machine of the present invention. These patents include U.S. Pat. Nos.: 5,797,157; 5,608,939; 5,548,860; 5,416,943; 5,127,124; 4,910,824; 4,633,541; 4,608,727; 4,590,635; 4,393,534; 4,358,868; 4,237,571; 4,122,576; 4,115,890; 3,619,848; 3,074,089; 2,817,977; 2,561,279; 2,348,268; 1,847,323; and 981,032.
Briefly described, the present invention relates to a gearbox arrangement coupling an input shaft to an output shaft, wherein the output shaft is driven by the input shaft in a constant rotational direction but at two different rotational speeds depending upon the particular direction of rotation of an input shaft for a given rotational speed of the input shaft. The present invention includes: an input shaft having an input gear integral therewith; an output shaft having an output gear integral therewith; a first unidirectional clutch coupling said input shaft with said output shaft such that rotation of said input shaft in a first input direction at a first input speed rotates said output shaft in a first output direction at a first output speed, but rotation of said input shaft in a second, opposite input direction causes said first unidirectional clutch to slip; an idler gear meshed with and driven by said input gear; an intermediate shaft having a first intermediate gear integral therewith, said first intermediate gear meshed with and driven by said idler gear; a second intermediate gear meshed with said output gear; and a second unidirectional clutch coupling said second intermediate gear with said intermediate shaft such that rotation of said input shaft in said second input direction at a second input speed rotates said output shaft in said first output direction at a second output speed, but rotation of said input shaft in said first input direction causes said second unidirectional clutch to slip.
In features of the present invention, the input shaft is coaxial to the output shaft; the first and second unidirectional clutches are coplanar; the unidirectional clutch is interposed within said output gear; the second unidirectional clutch is interposed within said second intermediate gear; the output gear is formed as part of said output shaft; and the input gear, the idler gear, and the first intermediate gear are coplanar.
In further features of the present invention, the first output speed differs from the second output speed when the first input speed equals the second input speed. Preferably, the first and input speeds each equal approximately 2000 rpm and the first output speed equals approximately 2000 rpm and the second output speed equals approximately 300 rpm.
The present invention also includes a floor maintenance machine utilizing the aforementioned gearbox arrangement whereby the machine can be selectively used for buffing, scrubbing, and stripping. The floor maintenance machine of the present invention further includes a switch for controlling the direction of rotation of the input shaft of the gearbox, and includes an adjustable floor support member for varying the weight supported by a pad of the machine against the floor surface.